gen_release_notes: resolve ambiguity by renaming `version` to `previous_version` and `next_version` to `this_version`

Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
Tested-by: Marge Bot <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4113>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/4113>
1 file changed